Final answer:
The first paragraph of The Dark Game supports the central idea that the Civil War was a long war by emphasizing the unexpected duration of the conflict.
Step-by-step explanation:
The first paragraph of The Dark Game supports the central idea that the Civil War was a long war by highlighting the unexpected duration of the conflict. It states that wars often last longer than anticipated and uses the example of the American Civil War to emphasize this point.
The paragraph mentions that Northerners and Southerners initially expected a quick resolution, but as the war continued, it became clear that there was no end in sight. This information demonstrates how the war was prolonged and supports the central idea that the Civil War was a long war.